Effects of juglone (5-hydroxy-1,4-naphthoquinone) on midgut morphology and glutathione status in Saturniid moth larvae.

Actias luna and Callosamia promethea larvae were fed birch foliage supplemented with juglone (5-hydroxy-1,4-naphthoquinone) to determine whether juglone causes oxidative stress in midguts of these species. Juglone is a substituent of walnut foliage. A. luna, but not C. promethea, thrives on walnut foliage, as well as birch foliage supplemented with juglone. After 2 and 3 days on juglone-containing diets, midgut samples from these animals were compared histologically and were analyzed for GSH and GSSG content. C. promethea, but not A. luna, midguts revealed partial loss of epithelial structure. In contrast, GSH and GSSG did not change significantly in either species. In a separate experiment, live midgut explants from each species were cultured for 4 h in 0, 0.05, and 0.25% juglone. In juglone-treated explants, GSSG increased 2.1 and 5.6-fold, respectively, for A. luna, and 1.6 and 2.7-fold, respectively, for C. promethea. There was also a small dose-dependent decrease in GSH in C. promethea, but not A. luna. Although histology indicates that the midgut is a target of juglone toxicity in C. promethea, GSH analyses from either species do not support the expectation that changes in GSH/GSSG explain differences in susceptibility to juglone toxicity.